Composition and process for treating the surface of aluminiferous metals

ABSTRACT

A highly corrosion resistant and paint adherent surface coating on aluminiferous metals can be provided very rapidly, if desired in less than one second, by contacting the surface with an aqueous acid liquid treating composition containing as solutes specified proportions of phosphate ions, titanium containing materials, fluoride, and an accelerator, the accelerator is preferably at least one of nitrous acid, nitric acid, tungstic acid, molybdic acid, permanganic acid, water soluble salts of all of these acids, and water-soluble organoperoxides.

TECHNICAL FIELD

This invention relates to a novel liquid surface treatment compositionand process for application to aluminiferous metals, which provide thesurface of aluminiferous metals, i.e., aluminum and aluminum alloyscontaining at least 65% by weight of aluminum, with an excellentcorrosion resistance and paint adherence. The present invention isapplied with particularly good effect in the surface treatment ofaluminum alloys in coil and sheet form.

BACKGROUND ART

Liquid compositions, which hereinafter are often called “baths” forbrevity, even if used by some other method than immersion, that are ingeneral use for treating the surface of aluminiferous metals can bebroadly classified into chromate types and nonchromate types. Chromicacid chromate conversion baths and phosphoric acid chromate conversionbaths are typical embodiments of chromate type treatment baths.

Chromic acid chromate conversion baths came into practical use in about1950 and are still widely used even at present for heat exchanger finstock and aviation vehicle components. The chromic acid chromateconversion baths contain chromic acid and fluoride as their maincomponents, with the fluoride functioning as a reaction accelerator.These baths coat metal surfaces with conversion coatings containing somequantity of hexavalent chromium.

Phosphoric acid chromate conversion baths originated with the inventiondisclosed in U.S. Pat. No. 2,438,877. These conversion baths, whichcontain chromic acid, phosphoric acid, and hydrofluoric acid as theirmain components, coat metal surfaces with conversion coatings whose maincomponent is hydrated chromium phosphate. Because these conversioncoatings do not contain hexavalent chromium, they also are in wide useat present, for such applications as underpaint coatings for beveragecan body and lid stock. Nevertheless, since these chromate type surfacetreatment baths do themselves contain toxic hexavalent chromium eventhough the coatings produced by them do not, hexavalent chromium-freetreatment baths are desired in view of the environmental problems fromdisposal of the baths, rinse waters, and the like.

Typical of the inventions in the field of the chromium-free nonchromatetype surface treatment baths is the process disclosed in Japanese PatentApplication Laid Open [Kokai or Unexamined] Number Sho 52-131937[131,937/1977]. The treatment bath in that reference consists of anacidic (pH approximately 1.5 to 4.0) aqueous coating solution containingphosphate, fluoride, and zirconium or titanium or both. Treatment of themetal surface with this surface treatment bath forms thereon aprotective coating whose main component is zirconium or titanium oxide.(This type of coating is often called a “conversion” coating, because itis believed that it also contains cations from the substrate in the formof oxides and/or phosphates.) An advantage of nonchromate surfacetreatment baths is that they are free of hexavalent chromium, and thisadvantage has resulted in their wide use at the present time fortreating the surface of drawn-and-ironed (“DI”) aluminum cans and thelike. However, the nonchromate baths require longer treatment times forcoating formation than chromate surface treatment baths. Shorteningsurface treatment times has become an important issue in the last fewyears, because of the increasingly high line speeds being used to boostproductivity. Moreover, nonchromate baths yield coatings with acorrosion resistance and paint adherence inferior to those of chromatecoatings.

The treatment process disclosed in Japanese Patent Application Laid Open[Kokai or Unexamined] Number Hei 1-246370 [246,370/1989] is an inventionwhose object is to shorten the aforementioned surface treatment times.In this process, the aluminiferous metal surface is first cleaned withan alkaline degreaser and the cleaned surface is then treated with anacidic (pH 1.5 to 4.0) aqueous solution containing 0.01 to 0.5 g/L ofzirconium ions, 0.01 to 0.5 g/L of phosphate ions, 0.001 to 0.05 g/L,measured as its stoichiometric equivalent as fluorine atoms, of “free”fluoride ions, and optionally 0.01 to 1 g/L of vanadium ions. However,when this process is applied to DI aluminum cans, the resulting filmdoes not always have a satisfactory resistance to blackening.

Another nonchromate treatment process is disclosed in Japanese PatentPublication Number Sho 57-39314 [39,314/1982]. Disclosed therein is atreatment process in which the aluminiferous metal surface is treatedwith an acidic solution containing hydrogen peroxide, one or moreselections from zirconium and titanium salts, and one or more selectionsfrom phosphoric acid and condensed phosphoric acids. However, thistreatment bath is unstable, and, in addition, is also inadequately rapidin terms of surface coating formation. Moreover, this document does notprovide a specific description or disclosure of the treatment time,treatment temperature, or treatment process.

It is for these reasons that nonchromate type surface treatment bathsare at present almost never used on surface treatment lines foraluminiferous metal coil or sheet where short treatment times arecritical.

In summary, then, there has yet to become established in the art acomposition or process for treating the surface of aluminiferous metalsthat can provide short treatment times and is capable of forming ahighly corrosion-resistant and strongly paint-adherent coating, but isfree of hexavalent chromium.

DISCLOSURE OF THE INVENTION

Problem(s) to Be Solved by the Invention

The present invention is directed to solving the problems describedabove for the prior art. In specific terms, the present inventionprovides a composition and process for treating the surface ofaluminiferous metals that are able to form rapidly a verycorrosion-resistant and highly paint-adherent coating on the surface ofaluminiferous metals.

SUMMARY OF THE INVENTION

It has been discovered that a surface treatment composition containingdissolved phosphate ions, dissolved titanium containing substance(s),and dissolved fluoride in particular relative quantities and aparticular relative quantity of accelerator selected from a specificgroup of chemical substances can rapidly form a very corrosion-resistantand highly paint-adherent coating on the surface of aluminiferousmetals. The present invention was achieved based on this discovery.

A concentrate or working composition according to the present inventionfor treating the surface of aluminiferous metals characteristicallycomprises, preferably consists essentially of, or more preferablyconsists of, water and the following materials in the relativeproportions stated as follows: from 0.010 to 5 parts by weight ofphosphate ions; from 0.010 to 2.0 parts by weight, calculated as itsstoichiometric equivalent as titanium atoms, of dissolved titaniumcontaining substance(s); from 0.010 to 12 parts by weight, calculated asits stoichiometric equivalent as fluorine atoms, of dissolved moleculesand/or anions containing fluorine; and from 0.010 to 2.0 parts by weightof dissolved accelerator. The bases for the specification of theseparticular weight proportions for each component will be explained insequence in the discussion of the composition of preferred surfacetreatment baths, vide infra. Counterions for the necessary constituentsexplicitly recited above are also necessary if needed for electricalneutrality.

The accelerator increases the speed of coating formation and is selectedfrom the group consisting of oxyacids, such as tungstic acid (i.e.,H₂WO₄), molybdic acid (i.e., HMoO₃), permanganic acid (i.e., HMnO₄),nitric acid (i.e., HNO₃), nitrous acid (i.e., HNO₂), hypochlorous acid(i.e., HClO), chlorous acid (i.e., HClO₂), chloric acid (i.e., HClO₃),bromic acid (i.e., HBrO₃), iodic acid (i.e., HIO₃), perchloric acid(i.e., HClO₄), perbromio acid (i.e., HBrO₄), periodic acid (i.e, HIO₄),orthoperiodic acid (i.e., H₅IO₆), and salts of oxyacids; peroxoacids,such as peroxomonosulfuric acid (i.e., H₂SO₅), peroxodisulfuric acid(i.e., H₂S₂O₈), peroxomonophosphoric acid (H₃PO₅), peroxodiphosphoricacid (i.e., H₄P₂O₈), peroxomonocarbonic acid (i.e., H₂CO₄),peroxodicarbonic acid (i.e., H₂C₂O₆), and any of the peroxoboric acids(i.e., HBO₃•½H₂O, HBO₄•H₂O, or HBO₅•H₂O), and salts of peroxoacids;higher valent metal cations of metals with at least two stable cationicvalence states, in cations that do not include oxygen, in aqueoussolution, such as tetravalent cerium (i.e., Ce⁺⁴), trivalent iron (i.e.,Fe⁺³), and tetravalent tin (Sn⁴⁺); hydrogen peroxide (H₂O₂); andwater-soluble organoperoxides. The use of an accelerator selected fromthis group in a treatment composition according to the present inventionyields a substantial improvement in the speed of formation of asufficiently thick coating to have protective qualities and in thecorrosion resistance and paint adherence of the coating thereby formed.

The four necessary active ingredients in a composition according to theinvention as described above need not necessarily all be provided byseparate chemical substances. For example, fluotitanic acid is wellsuited to be a single source of both titanium and fluoride.

A process according to the present invention for treating the surface ofaluminiferous metals characteristically comprises the formation thereonof a coating by bringing the surface of aluminiferous metal intocontact, at a temperature from normal ambient temperature (i.e., atleast 10 and more often at least 20° C.) to 80° C., with a surfacetreatment working composition, and thereafter subjecting the surface ofthe aluminiferous metal carrying the surface treatment bath to a rinsewith water and, usually, drying, often with the use of heat.

DETAILED DESCRIPTION OF THE INVENTION, INCLUDING PREFERRED EMBODIMENTS

The source of the phosphate ions for a concentrate or workingcomposition according to the present invention can be one or moreselections from orthophosphoric acid (i.e., H₃PO₄) and neutral and acidsalts thereof and condensed phosphoric acids, such as pyrophosphoricacid (i.e., H₄P₂O₇) and tripolyphosphoric acid (i.e., H₅P₃O₁₀) andneutral and acid salts of any of these. The particular phosphate ionssource selected is not critical, and the stoichiometric equivalent asphosphate ions from any of these sources is considered to be phosphateions for determining whether a composition is according to the inventionand if so, what its degree of preference is, irrespective of the actualextent of ionization and condensation to form chemical species withP—O—P bonds that may exist in solution. The phosphate ions content in aworking bath according to the present invention is preferably from 0.010to 5.0 g/L, more preferably from 0.050 to 5.0 g/L, and even morepreferably from 0.30 to 2.0 g/L. While a coating may be formed even at aphosphate ions concentration below 0.010 g/L, such coatings do not havean excellent corrosion resistance or paint adherence. The use of largeconcentrations—in excess of 5.0 g/L—is uneconomical: While good-qualitycoatings are formed at such levels, no additional benefits are obtainedfrom the use of such large amounts, so that the cost of the treatmentbath is raised without any offsetting benefit.

The source of the titanium containing substance(s) in a working orconcentrate composition according to the present invention preferably iseither a salt containing titanium and/or titanyl cations, the anions ofwhich salt can be sulfate, fluoride, or the like, or fluotitanic acid orat least one of its salts, but the selection of the titanium containingsubstance(s) is not critical. The titanium containing substance(s)concentration in a surface treatment bath according to the inventionshould be from 0.010 to 2.0 g/L and is preferably from 0.10 to 2.0 g/Lor more preferably from 0.10 to 1.0 g/L, in each instance calculated astitanium. The rapid formation of a satisfactory coating becomes quiteproblematic at a titanium content below 0.010 g/L. The use of largeamounts—in excess of 2.0 g/L—is uneconomical: While good-qualitycoatings are formed at such levels, no additional benefits are obtainedfrom the use of such large amounts and the cost of the treatment bath israised.

The source of fluoride in the composition and surface treatment bathaccording to the present invention can be such fluorine-containing acidsas hydrofluoric acid (i.e., HF), fluotitanic acid (i.e., H₂TiF₆),fluosilicic acid (i.e., H₂SiF₆), and fluozirconic acid (i.e., H₂ZrF₆),as well as any of their neutral and acid salts, but again the selectionof the fluoride is not critical. The fluoride content in the surfacetreatment bath should be in the range from 0.010 to 12 g/L, preferablyis from 0.050 to 5.0 g/L, and more preferably is from 0.10 to 3.0 g/L,in each case calculated as fluorine.

Aluminum ions eluting from the substrate are stabilized in the bath asaluminum fluoride by the fluoride, and the content levels given aboveinclude the quantity of fluoride necessary to do this. Aluminum fluoridehas little effect on the coating-forming reactions. For example, afluorine concentration of about 0.2 g/L is required in order tostabilize an aluminum concentration in the surface treatment bath of 0.1g/L. Not counting the amount of fluorine required to produce aluminumfluoride, the optimal fluoride content for coating formation is from0.010 to 5.0 g/L and preferably from 0.10 to 3.0 g/L, in each casecalculated as fluorine. A fluorine content below 0.010 g/L results in aninadequate reactivity and hence in inadequate coating formation. On theother hand, levels in excess of 12 g/L result in an increased degree ofetching that causes an undesirable unevenness in appearance, and suchhigh levels also greatly complicate effluent treatment.

The accelerator functions in a surface treatment process according tothe present invention to accelerate the rate of formation of thetitanium coating on the metal surface and also to induce the formationof a highly corrosion-resistant and strongly paint-adherent coating. Theaccelerator concentration in the surface treatment bath must be in therange from 0.010 to 2.0 g/L and is preferably in the range from 0.10 to1.1 g/L. No acceleration of the film-forming reaction is usuallyobserved at an accelerator concentration below 0.010 g/L. The benefitsfrom the accelerator do not further increase at accelerator levels inexcess of 2.0 g/L, so that additions in excess of this level simplyraise costs and are thus uneconomical.

An especially preferred accelerator includes at least one selection fromthe group consisting of nitrous acid, nitric acid, tungstic acid,molybdic acid, permanganic acid, all water-soluble salts of all of theseacids, and water-soluble organoperoxides.

The nitrous acid/nitrite source is not critical as long as it iswater-soluble; however, the use of the sodium salt (i.e., NaNO₂) or thepotassium salt (i.e., KNO₂) of nitrous acid is usually preferred becauseof their relatively low cost. The nitric acid/nitrate source is also notcritical, again as long as it is water-soluble; however, the use of thesodium salt (i.e., NaNO₃) or the potassium salt (i.e., KNO₃) of nitricacid (i.e., HNO₃) or of nitric acid itself is preferred because of theirrelatively low cost.

The tungstic acid/tungstate source is not critical as long as it iswater-soluble; however, again the use of the sodium salt (i.e., Na₂WO₄)or potassium salt (i.e., K₂WO₄) of tungstic acid is preferred because oftheir relatively low cost.

The molybdic acid/molybdate source is not critical as long as it iswater-soluble; however, the use of the sodium salt (i.e., Na₂MoO₄) orammonium salt (i.e., (NH₄)₆Mo₇O₂₄) of simple or condensed molybdic acidrespectively is preferred because of their relatively low cost.

The permanganic acid/permanganate selection is not critical as long asit is water-soluble; however, the use of the sodium salt (i.e., NaMnO₄)or potassium salt (i.e., KMnO₄) of permanganic acid is preferred becauseof their relatively low cost.

Preferred examples of water-soluble organoperoxide are tert-butylhydroperoxide (i.e., (CH₃)₃C—O—OH), tert-hexyl hydroperoxide (i.e.,CH₃CH₂(CH₃)₂C—O—OH), and di-tert-butyl peroxide (i.e.,(CH₃)₃C—O—O—C(CH₃)₃).

A working surface treatment bath according to the present invention ismost conveniently prepared from a concentrate composition according tothe present invention, and the pH of a working bath must be in the rangefrom 1.0 to 4.5. A pH below 1.0 causes an excessive etch of the metalsurface by the treatment bath and thereby strongly impairs filmformation. It becomes very problematic to obtain a highlycorrosion-resistant and strongly paint-adherent coating at a pH inexcess of 4.5. The more preferred pH range is 1.3 to 3.0. The pH of thesurface treatment bath according to the present invention can beadjusted by adding an acid, e.g., nitric acid, sulfuric acid,hydrofluoric acid, or the like to lower the pH, or by adding an alkali,e.g., sodium hydroxide, sodium carbonate, ammonium hydroxide, or thelike to raise the pH.

When in the practice of the present invention the metal substrate iscomposed of an alloy of aluminum with copper or manganese, the stabilityof the treatment bath may be substantially impaired by dissolution intothe surface treatment bath of metal ions derived from the copper ormanganese alloying component. In such a case, a difunctional organicacid or its alkali metal salt may be added as metal sequestering agentin order to chelate the aforementioned alloying metal ions. Examples ofsuitable organic acids are gluconic acid, heptogluconic acid, oxalicacid, tartaric acid, and ethylenediaminetetraacetic acid.

A working surface treatment bath according to the present invention maybe brought into contact with the substrate to be treated by anyconvenient method and normally is used as part of a process sequenceincluding other steps. A preferred generalized process sequence, forexample, is as follows:

1. Surface cleaning: degreasing with an acidic, alkaline, orsolvent-based system

2. Water rinse

3. Surface treatment with treatment bath according to the presentinvention treatment temperature: ambient temperature to 80° C. treatmenttime: 0.5 to 60 seconds treatment technique: spraying or dipping

4. Water rinse

5. Rinse with deionized water

6. Drying.

A treatment process according to the present invention is performed bybringing a working surface treatment bath as described above intocontact with a surface of aluminiferous metal at from room temperatureto 80° C. and preferably at from 35° C. to 70° C., for a contact timethat is at least, with increasing preference in the order given, 0.50,1.0, or 2.0 seconds and independently preferably is not more than, withincreasing preference in the order given, 120, 90, 60, 50, 40, 30, 20,10, 8.0, 5.0, 3.0, or 2.5 seconds. Treatment times below 0.5 second areassociated with an insufficient reaction and hence may not yield theformation of a coating with good corrosion resistance and paintadherence. The properties of the coating do not usually improve furtherat treatment times above 120 seconds and in some instances do notimprove further even after treatment times of a few seconds, while anyextended treatment time increases the process cost.

The coating formed in a process according to the invention preferablycontains a mass per unit area of 3 to 50, or more preferably of 5 to 30,milligrams per square meter (hereinafter usually abbreviated as “mg/m²”)of titanium atoms, which are measured as such by some method, such asX-ray fluorescence, that is independent of the chemical nature of thetitanium atoms. When the surface coating mass is below 3 mg/M² astitanium, there is usually inadequate corrosion resistance by theresulting coating. At the other end of the range, there is usually anunsatisfactory paint adherence by the coating when the coating weightexceeds 50 mg/m².

The aluminiferous metals that may be subjected to surface treatment by aprocess according to the present invention encompass both pure aluminumand aluminum alloys, for example, Al—Cu, Al—Mn, Al—Mg, Al—Si, and Al—Znalloys. The form and dimensions of the aluminiferous metal used in theinvention process are not critical, and, for example, sheet and variousmolding shapes fall within the scope of the process.

Surface treatment baths and process according to the present inventionwill be illustrated in greater detail in the following through bothworking and comparison examples.

EXAMPLES

The treatment process sequence and other conditions outlined immediatelybelow apply to each of Examples 1 to 9 and Comparison Examples 1 to 7.

Sample Material

Aluminum-magnesium alloy sheet according to Japanese Industrial Standard(hereinafter usually abbreviated as “JIS”) 5182 was used.

Dimensions: 300 millimeters (hereinafter usually abbreviated as“mm”)×200 mm.

Sheet thickness: 0.25 mm

Treatment Conditions

The conversion-treated sheet was prepared by the execution of thefollowing processes in the sequence 1→2→3→4→5→6.

1. Degreasing (60° C., 10 seconds, spray) A 2% aqueous solution of acommercially available alkaline degreaser, FINECLEANER® 4377K from NihonParkerizing Company, Limited, was used.

2. Water rinse (ambient temperature, 10 seconds, spray)

3. Metal treatment according to the invention or a comparison thereto(spray)

The components used in the surface treatment baths, their concentrationsin these baths, and the conditions for the processes according to theinvention in Examples 1 to 9 and for Comparison Examples 1 to 5 areshown in tables below. The surface treatment conditions for ComparisonExamples 6 and 7 are noted separately. An aqueous solution of 40%fluotitanic acid—a compound that is both a titanium containingsubstance(s) and a fluoride—was used in Examples 1, 4, 7, and 9 and inComparison Example 2 as the source of both of these necessary componentsof a bath according to the invention. The entire amount of fluotitanicacid used is shown in the tables below under one column heading as atitanium source and under another heading as a fluoride source, but theamount was not in fact duplicated in the working bath. An aqueoussolution of 67.5% nitric acid was used both as an accelerator and for pHadjustment in Examples 1 and 5.

4. Water rinse (ambient temperature, 10 seconds, spray)

5. Rinse with deionized water (ambient temperature, 5 seconds, spray)

6. Heating and drying (80° C., 3 minutes, hot-air oven)

A small sprayer was used for the degreasing, water rinse, rinse withdeionized water, and treatment according to the invention or acomparison thereto. The particular small sprayer used was designed toreproduce the same spraying conditions as in a continuous surfacetreatment line for the actual treatment of aluminum alloy coil.

The following methods were used to test the coating weight, corrosionresistance, and paint adherence of the treated specimens.

(1) Coating Weight

The Ti or Zr add-on, in mg/m² on the treated sheet was measured using afluorescent x-ray analyzer (RIX1000 from Rigaku Denki Kogyo KabushikiKaisha).

(2) Corrosion Resistance

Salt-spray testing according to JIS Z 2371 was used to evaluate thecorrosion resistance. The development of corrosion on the treated sheetwas visually evaluated after 150 hours of salt-spray testing, and theresults were scored according to the following scale:

+++: corroded area was less than 10%; ++: corroded area was greater thanor equal to 10%, but less than 50%; +: corroded area was greater than orequal to 50%, but less than 90%; x: corroded area was greater than orequal to 90%.

(3) Paint Adherence

The surface of the conversion-treated aluminum-magnesium alloy sheet waspainted with an epoxy-phenol paint for can lids to give a paint filmthickness of 8 micrometers followed by baking for 3 minutes at 220° C.Polyamide film was then inserted between two of these painted surfaceswith hot-press bonding at 200° C. for 2 minutes. The hot-press bondedcomposite was cut into 10 mm wide×120 mm long strips, which were thetest specimens. A test specimen was peeled from the polyamide film usingthe T-peel test procedure, and the peel strength at this point wasdesignated as the primary adherence. In order to evaluate the durabilityof the adherence to water, a test specimen prepared as described abovewas dipped in boiling deionized water for 60 minutes and then submittedto measurement of the peel strength in the same T-peel test procedure.The result in this case was designated as the secondary adherence.

Larger values for the peel strength are indicative of a better paintadherence. A performance sufficient for practical applications was apeel strength of at least 7.0 kilograms-force (hereinafter usuallyabbreviated as “kgf”)/10 mm width in the case of the primary adherenceand a peel strength of at least 5.0 kgf/10 mm width in the case of thesecondary adherence.

Comparison Example 6

The same treatment process was run as in Example 1, except for using a2% aqueous solution of a commercially available zirconium-basedtreatment agent, ALODINE™ 4040 from Nihon Parkerizing Company, Limited,as the surface treatment bath in process step 3. This treatment bath wassprayed on the same aluminum-magnesium alloy sheet as described abovefor 30 seconds at 40° C. The test results are reported in tables below.

Comparison Example 7

The same treatment was run as in Example 1, except for using a 2%aqueous solution of a commercially available zirconium-based treatmentagent, ALODINE™ 4040, from Nihon Parkerizing Company, Limited, as thetreatment bath. This bath was sprayed on the same aluminum-magnesiumalloy sheet as described above for 5 seconds at 40° C. The test resultsare reported in tables below.

Benefits of the Invention

As the preceding description has made clear, application of a workingtreatment composition in a surface treatment process according to thepresent invention to aluminiferous metals rapidly forms a highlycorrosion-resistant and strongly paint-adherent coating on the metalsurface prior to the painting or forming thereof. Moreover, when thesubstrate aluminiferous metal is in the form of continuous coil orsheet, rapidity of the treatment supports higher production line speedsand permits compactness (space savings) of the treatment facilities.

In consequence of these effects, surface treatment concentrates, workingbaths, and processes according to the present invention for applicationto aluminiferous metals have a very high degree of practical utility.

TABLE 1 COMPONENTS USED IN THE TREATMENTS OF EXAMPLES 1 TO 9 ANDCOMPARISON EXAMPLES 1 TO 5, AND IDENTIFYING SYMBOLS THEREFOR SourceMaterial(s) Chemical Component Compound Formula Symbol Phosphate ions85% Orthophosphoric acid in water H₃PO₄ a Titanium 40% Fluotitanic acidin water H₂TiF₆ A containing 24% Titanic sulfate in water Ti(SO₄)₂ Bsubstance(s) Titanyl sulfate in water, 10% Ti TiOSO₄ C Fluoride 40%Fluotitanic acid in water H₂TiF₆ A 20% Hydrofluoric acid in water HF a40% Fluosilicic acid in water H₂SiF₆ b 96% Ammonium acid fluoride inwater NH₄HF₂ c Accelerator 67.5% Nitric Acid in water HNO₃ T Potassiumpermanganate KMnO₄ U 97% Pure Sodium Nitrite NaNO₂ V Sodium tungstatedihydrate Na₂WO₄.2H₂O W Ammonium heptamolybdate (NH₄)₆Mo₇O₂₄.4H₂O Xtetrahydrate 69% Tert-butyl hydroperoxide in water (CH₃)₃C—O—OH Y 5%Stannic chloride in water SnCl₄ Z pH Regulator 67.5% Nitric acid inwater HNO₃ T 97% Sulfuric acid in water H₂SO₄ a 25% ammonia in waterNH₄OH b

TABLE 2 COMPOSITIONS OF SURFACE TREATMENT BATHS ACCORDING TO THEINVENTION Grams per Liter in Bath of: Ti Com- Phosphate FluorideAccelerator pH pH Example pound/ Source/ Source/ Source/(ActiveRegulator of Number (Ti) (PO₄ ⁻³) (F) Accelerator) Type Bath 1 5.0 of A/1.0 of a/ 5.0 of A/ 1.00 of T/ T 1.3 (0.58) (0.82) (1.39) (0.68) 2 2.0of C/ 0.2 of a/ 0.5 of a/ 0.10 of W/ a 1.8 (0.20) (0.16) (0.10) (0.09) 330.0 of B/ 4.0 of a/ 15.0 of a/ 0.50 of V/ a 1.0 (1.44) (3.30) (2.85)(0.49) 4 10.0 of A/ 1.0 of a/ 10.0 of A/ {1.00 of V/ b 1.5 (1.17) (0.82)(2.78) (0.97)} + {0.10 of U/(0.10)} 5 20.0 of B/ 1.5 of a/ {0.5 of a/{0.30 of T/ T 1.3 (0.96) (1.24) (0.10} + (0.20)} + {0.05 {0.5 of b/ ofX/(0.05)} (0.16) 6 5.0 of C/ 1.0 of a/ 2.0 of c/ {0.30 of Y/ b 4.2(0.48) (0.82) (1.28) (0.21)} + {0.10 of W/(0.10)} 7 {0.30 of 2.5 of a/{3.0 of A/ 1.0 of Y/ b 2.5 A/ (2.06) (0.83)} + (0.69) (0.35)} + {2.0 ofc/ {5.0 of C/ (1.28)} (0.50)} 8 1.0 of B/ 0.04 of a/ 0.2 of b/ 0.03 ofU/ b 4.0 (0.05) (0.03) (0.06) (0.03) 9 2.0 of A/ 0.5 of a/ 2.0 of A/3.00 of Z/ a 1.6 (0.23) (0.41) (0.56) (0.15)

TABLE 3 COMPOSITIONS OF SURFACE TREATMENT BATHS FOR COMPARISON EXAMPLES1 TO 5 Compar- Grams per Liter in Bath of: ison Ti Com- PhosphateFluoride Accelerator pH pH Example pound/ Source/ Source/ Source/(ActiveRegulator of Number (Ti) (PO₄ ⁻³) (F) Accelerator) Type Bath 1 none 1.0of a/ 0.5 of b/ 1.00 of V/ a 1.3 (0.82) (0.16) (0.97) 2 5.0 of A/ none5.0 of A/ 0.30 of W/ b 1.6 (0.58) (1.39) (0.27) 3 10.0 of C/ 1.5 of a/none 1.0 of Y/ a 1.2 (1.00) (1.24) (0.69) 4 30.0 of B/ 4.0 of a/ 5.0 ofa/ 0.5 of V/ b 5.0 (1.44) (3.30) (0.95) (0.49) 5 10.0 of B/ 1.0 of a/5.0 of a/ none b 1.5 (0.48) (0.82) (0.95)

TABLE 4 PROCESS CONDITIONS AND EVALUATION TEST RESULTS Conditions DuringExample Treatment According (“Ex”) or to the Invention or ComparisonComparison Rating Example Contact Add-on after 150 Paint Adherence,(“CE”) Temper- Time, Mass of Hour Salt kgf/10 mm of Width Number ature,° C. Seconds Ti, mg/m² Spray Test Primary Secondary Ex 1 40 6 15 +++10.8 8.3 Ex 2 45 40 20 +++ 9.4 6.7 Ex 3 40 5 12 +++ 9.0 6.7 Ex 4 65 2 15+++ 11.4 9.2 Ex 5 35 5 4.5 +++ 10.5 9.0 Ex 6 45 8 43 +++ 9.3 6.8 Ex 7 604 25 +++ 8.9 7.8 Ex 8 35 50 9.0 +++ 7.5 5.3 Ex 9 50 12 20 +++ 7.2 5.5 CE1 50 10 0 × 3.8 1.0 CE 2 55 5 20 + 6.0 2.9 CE 3 35 40 1.0 × 4.0 1.3 CE 445 8 17 ++ 5.2 3.4 CE 5 60 30 2.0 × 5.0 1.3 CE 6 40 30 *18 of Zr ++ 7.25.0 CE 7 40 5  *5 of Zr + 4.6 2.7 Footnote for Table 4 *There is notitanium added in these comparison examples, which used a treatmentcomposition that does not contain titanium.

What is claimed is:
 1. An aqueous liquid composition that is suitablefor treating the surface of aluminiferous metals to form a corrosionprotective and paint-adherent coating thereon, said compositioncomprising the following components in relative amounts as recitedbelow: (A) from 0.01 to 5 parts by weight of dissolved phosphate ions;(B) from 0.1 to 2 parts by weight, calculated as their stoichiometricequivalent as titanium atoms, of dissolved molecules, ions, or both thatcontain titanium atoms; (C) from 0.05 to 5 parts by weight, calculatedas their stoichiometric equivalent as fluorine atoms, of dissolvedmolecules, anions, or both that contain fluorine atoms; and (D) from0.01 to 2 parts by weight of water soluble accelerator that is acombination of (a) sodium nitrite and potassium permanganate or (b)nitric acid and ammonium heptamolybdate.
 2. A composition according toclaim 1, wherein the accelerator further comprises at least one materialselected from the group consisting of nitrous acid, permanganic acid,water-soluble salts of all of the preceding acids, and water-solubleorganoperoxides, and, optionally, also contains nitrate ions.
 3. Aworking composition according to claim 2, wherein the composition has apH from 1.0 to 4.5 and contains from 0.01 to 5 g/L of dissolvedphosphate ions, from 0.01 to 2 g/L of dissolved molecules that containtitanium atoms, calculated as titanium atoms; from 0.01 to 12 g/L ofdissolved molecules that contain fluorine atoms, calculated as fluorineatoms; and 0.01 to 2 g/L of accelerator.
 4. A working compositionaccording to claim 3, wherein the composition contains from 0.05 to 5g/L of dissolved phosphate ions, from 0.10 to 2 g/L of dissolvedmolecules that contain titanium atoms, calculated as titanium atoms; andfrom 0.05 to 5.0 g/L of dissolved molecules that contain fluorine atoms,calculated as fluorine atoms.
 5. A working composition according toclaim 4, wherein the composition has a pH from 1.3 to 3.0 and containsfrom 0.30 to 2.0 g/L of dissolved phosphate ions, from 0.10 to 1.0 g/Lof dissolved molecules that contain titanium atoms, calculated astitanium atoms; from 0.10 to 2.0 g/L, calculated as fluorine atoms, ofdissolved molecules, anions, or both that contain fluorine atoms; andfrom 0.10 to 1.1 g/L of accelerator.
 6. A working composition accordingto claim 1, wherein the composition has a pH from 1.0 to 4.5 andcontains from 0.01 to 5 g/L, of dissolved phosphate ions; from 0.01 to 2g/L, of dissolved molecules that contain titanium atoms, calculated astitanium atoms; from 0.01 to 12 g/L of dissolved molecules that containfluorine atoms, calculated as fluorine atoms; and 0.01 to 2 g/L ofaccelerator.
 7. A working composition according to claim 6, wherein thecomposition contains from 0.05 to 5 g/L of dissolved phosphate ions;from 0.10 to 2 g/L of dissolved molecules that contain titanium atoms,calculated as titanium atoms; and from 0.05 to 5.0 g/L of dissolvedmolecules that contain fluorine atoms, calculated as fluorine atoms. 8.A working composition according to claim 7, wherein the composition hasa pH from 1.3 to 3.0 and contains from 0.30 to 2.0 g/L of dissolvedphosphate ions; from 0.10 to 1.2 g/L of dissolved molecules that containtitanium atoms, calculated as titanium atoms; from 0.10 to 2.8 g/L ofdissolved fluorine atoms, calculated as fluorine atoms; and from 0.10 to1.1 g/L of accelerator.
 9. A process for treating an aluminiferous metalsurface, said process comprising steps of: (I) bringing thealuminiferous metal surface into contact, at a temperature from normalambient temperature to 80° C., with a working composition according toclaim 8 for a time of at least 0.5 second; and (II) discontinuing thecontact established in step (I) and thereafter subjecting thealuminiferous metal surface carrying residue of the surface treatmentbath to a rinse with water; and, optionally, (III) drying the rinsedsurface from the end of step (II).
 10. A process according to claim 9,wherein a coating weight of from 3 to 50 mg/m² calculated as titanium isproduced on the aluminiferous metal surface during the process.
 11. Aprocess for treating an aluminiferous metal surface, said processcomprising steps of: (I) bringing the aluminiferous metal surface intocontact, at a temperature from normal ambient temperature to 80° C.,with a working composition according to claim 7 for a time of at least0.5 second; and (II) discontinuing the contact established in step (I)and thereafter subjecting the aluminiferous metal surface carryingresidue of the surface treatment bath to a rinse with water; and,optionally, (III) drying the rinsed surface from the end of step (II).12. A process according to claim 11, wherein a coating weight of from 3to 50 mg/M² calculated as titanium is produced on the aluminiferousmetal surface during the process.
 13. A process for treating analuminiferous metal surface, said process comprising steps of: (I)bringing the aluminiferous metal surface into contact, at a temperaturefrom normal ambient temperature to 80° C., with a working compositionaccording to claim 6 for a time of at least 0.5 second; and (II)discontinuing the contact established in step (I) and thereaftersubjecting the aluminiferous metal surface carrying residue of thesurface treatment bath to a rinse with water; and, optionally, (III)drying the rinsed surface from the end of step (II).
 14. A processaccording to claim 13, wherein a coating weight of from 3 to 50 mg/m²calculated as titanium is produced on the aluminiferous metal surfaceduring the process.
 15. A process for treating an aluminiferous metalsurface, said process comprising steps of: (I) bringing thealuminiferous metal surface into contact, at a temperature from normalambient temperature to 80° C., with a working composition according toclaim 5 for a time of at least 0.5 second; and (II) discontinuing thecontact established in step (I) and thereafter subjecting thealuminiferous metal surface carrying residue of the surface treatmentbath to a rinse with water; and, optionally, (III) drying the rinsedsurface from the end of step (II).
 16. A process according to claim 15,wherein a coating weight of from 3 to 50 mg/m² calculated as titanium isproduced on the aluminiferous metal surface during the process.
 17. Aprocess for treating an aluminiferous metal surface, said processcomprising steps of: (I) bringing the aluminiferous metal surface intocontact, at a temperature from normal ambient temperature to 80° C.,with a working composition according to claim 4 for a time of at least0.5 second; and (II) discontinuing the contact established in step (I)and thereafter subjecting the aluminiferous metal surface carryingresidue of the surface treatment bath to a rinse with water; and,optionally, (III) drying the rinsed surface from the end of step (II).18. A process according to claim 17, wherein a coating weight of from 3to 50 mg/m² calculated as titanium is produced on the aluminiferousmetal surface during the process.
 19. A process for treating analuminiferous metal surface, said process comprising steps of: (I)bringing the aluminiferous metal surface into contact, at a temperaturefrom, normal ambient temperature to 80° C., with a working compositionaccording to claim 3 for a time of at least 0.5 second; and (II)discontinuing the contact established in step (I) and thereaftersubjecting the aluminiferous metal surface carrying residue of thesurface treatment bath to a rinse with water; and, optionally, (III)drying the rinsed surface from the end of step (II).
 20. A processaccording to claim 19, wherein a coating weight of from 3 to 50 mg/m²calculated as titanium is produced on the aluminiferous metal surfaceduring the process.
 21. A composition according to claim 1, wherein saidaccelerator further comprises at least one material selected from thegroup consisting of nitrous acid, nitric acid, permanganic acid, watersoluble salts of these acids, and water soluble organoperoxides.
 22. Acomposition according to claim 1 further comprising a difunctionalorganic acid or its alkali metal salt sequestering agent for copper oraluminum ions dissolved into said composition wherein said difunctionalorganic acid is selected from the group consisting of heptogluconicacid, oxalic acid, tartaric acid, and ethylenediaminetetraacetic acid.